Gas bubble disease

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The gas bubble disease (GBK) of fish arises when more gases in the water in total dissolved is, as the diffusion equilibrium corresponds with the air. One then speaks of gas oversaturation , which can be determined with the help of a saturometer .

GBK can take very different forms, depending on how strong the gas oversaturation is and how long it has been going on.

In acute cases, large blisters form in the skin between the fin rays and in the scale pockets, so that the fish can look like pine cones. Fish fry can be really "blown up". After such injuries, extensive fungal infections often form on the skin. In most cases, however, the fish die acutely.

If there is weak gas oversaturation for a long time, the bubbles usually appear gradually in the blood vessels, especially in the gills. Parts of the gills can die off as a result of the gas embolism or the gas bubbles collect in the heart and lead to circulatory failure. Often times, gas builds up behind one of the eyes and eventually drives it out of the cavity. The fish become blind on one side and usually turn dark on this side of the body.

There is disagreement in the literature as to which parameter of gas oversaturation is decisive for the development of GBK. Nitrogen oversaturation is blamed primarily on the fishing industry (Leyendecker, Knösche, Hönig et al.). On the other hand, limnologists and physicists, as well as in the more recent American fishing literature, see total supersaturation with the sum of all dissolved gases as the cause of the bubble formation. This position also agrees with the way the Saturometer works and with physical considerations of gas diffusion between water and gas bubbles. According to this, a bubble can only grow and consequently only develop if it has a positive balance of diffusion of all gas molecules. A separate "supersaturation" of nitrogen with a simultaneous shortage of other gases cannot alone cause a positive balance. On the other hand, an oversaturation with oxygen has the same physical effect as that of any other gas. In fact, GBK is also observed under conditions of strong oxygen supersaturation, provided that the sum of the partial pressures of all dissolved gases is higher than the hydrostatic, i.e. mechanical pressure in the vicinity of the bubbles.

Fish are also significantly more susceptible to infectious diseases under the influence of weak gas oversaturation. In rainbow trout infected with infectious pancreatic necrosis , the death rate increased from 35% to 65% if they were additionally exposed to gas (over) saturation of only 101–103%. With this weak gas oversaturation, only 9% of uninfected fish died directly from gas bubble disease (Baath et al.).

literature

  • Ch. Baath, K. Bauer, J. Weikel, H. Wiedemann, G. Wizigmann: Influence of gas oversaturation in water on infectious diseases in rainbow trout. In: K. Lillelund, H. Rosenthal: Fish Health Protection Strategies. BMFT, Hamburg / Bonn 1989.
  • M. Bohl: gas bubble disease in fish. In: Tierärztl. Practice. 25, 1997, pp. 284-288.
  • DH Fickeisen, MJ Schneider, GA Wedemeyer: Gas Bubble Disease. In: Trans.Am.Fish.Soc. 109, (6), 1980, pp. 657-771.
  • J. Hönig, W. Hoffmann, W. Scholl: On gas bubble disease in fish. In: Fischer and Teichwirt. 9, 1979, pp. 116-120.
  • R. Knösche: Problems of gas bubble disease in intensive fish production. In: Zeitschr. fd inland fisheries of the GDR. 2, 1985, pp. 44-50.
  • WF Crisis, JW Meade: Effects of low-level gas supersaturation on lake trout (Salvelinus namaycush). In: Can. J. Fish. Aquat. Sci. 45, 1988, pp. 666-674.
  • H. Kuhlmann: On the gas bubble disease in fish. In: The fish host. 37, 12, 1987, pp. 87-88.
  • WE Leyendecker: Fish tolerance to Dissolved Nitrogen. Thesis . New Mexico State University, 1969.
  • A. Mohr: Gas oversaturation and gas bubble disease. In: Fischer and Teichwirt. No. 1, 1982, pp. 37-40.
  • MC Marsh, FP Gorham: The gas disease in fishes. In: Report US Bur. Fish. 1904, pp. 343-376.
  • DE Weitkamp, ​​M. Katz: A review of Dissolved Gas Supersaturation Literature. In: Trans. Am. Fish. Soc. 109, 1980, pp. 659-702.